Nichrome Wire

If you have observed the way a toaster works, you would surely know how the infrared radiation works in heating breads and toasts. A small thin wiring in your toaster, that aids in heating your toasts is known as nichrome wire! A nichrome wire is usually wrapped around a mica sheet of a toaster to generate the infrared radiation. But what is nichrome? It is a non magnetic alloy made of nickel (also known as Ni₂₈ and 80% by weight in alloy) and chromium (also known as Cr₂₄ and 20% by weight). Pertaining to its corrosion resistant properties, this wire is used in heating elements (devices where heat is converted into electricity through Joule heating) like toasters, ovens, hair dryers, etc.

Nichrome Wire Properties
Nichrome is an excellent conductor of heat and is used quite a lot as a heating element because of the two properties mentioned below:

1. This wire has a high resistivity and a very high boiling point.
2. It is quite resistant to oxidation and hence is a better substitute for iron, which on the contrary, rusts due to oxidation.

Color	Silvery gray
Melting Point	1400 ºC
Resistance at room temperature	1.0 x 10-6 - 1.5 x 10-6ohm m
Temperature Coefficient of resistance	100 ppm/ºC (at 25 ºC - 100 ºC)
Thermal Conductivity	11.3 W/mºC
Density	8400 kg/m3
Specific Heat	450 J/kgºC
Modulus of elasticity	2.2 x 1011
Specific gravity	8.4
Thermal Expansion Coefficient	13.4 x 10-6/ºC (at 20ºC - 100ºC)
Operating temperature	900 ºC

How and Where to Buy Nichrome Wire
Explosives, fireworks, ceramics and many industries that use heating applications use nichrome wire. It also finds a major application in microbiological lab apparatus and motorcycle silencers. In case of power supplies and instrumentation, insulated wires are used.

Nichrome wire comes in various gauges of which 40 wire gauge and 14 wire gauge are quite popular. The 40 gauge nichrome wire is very thin and is used in igniters that are used to ignite a model rocket motor or an ejection charge. Heater elements use 26 - 32 gauge wire. For foam cutting, one may require a wire of 22 - 28 gauge. Kilns used for firing ceramics, use 14-18 gauge wire, pertaining to the high heat resistance factor of this alloy. However, the heat generated depends on the length of the wire and voltage supply. There are many online stores which ship you this product depending on your requirement and use. Apogee Components, Aerocon Systems, Omega, McMaster-Carr and Pelican Wire are a few firms that produce nichrome wires for commercial applications. In fact, many of the defense/aerospace applications, dental work, floor heating wires and plastic cutting machines are supplied with this alloy by Pelican Wire. Even as this product finds its application in propellant motors, to increase its reliability, a pyrogen tip is often added in the tip for ignition. But, this process requires a permit from the government.

Nichrome wire is definitely a good choice for heating appliances. However, it is costlier than copper because both nickel and chromium are costly metals. If you are planning out some experiments with this wiring, make sure that you do it under the guidance of an electrician.